rough idle and PO 171 code

[biswrest]

My mounty just started to have a rough idle and killed twice at idle in park. It appears to be running smooth besides that. I took it to I Reilly's and it came up with two PO 171 codes and running lean. Any help would be appreciated.

 

[Number4]

What size engine?
Has the battery been disconnected recently?

 

[lincolnshibuya]

if you have the 4.6V8 Mounty, then it's a vacuum leak.

https://www.facebook.com/photo.php?...20988871.20343.110528882348605&type=3&theater

 

[biswrest]

4.6

It is a 2003 4.6 V-8 Mountaineer. Last night I tried the best I could looking for a vacuum leak, using an unlit propane torch. I came up empty, not hearing anything different. Should I change the upstream O2 sensor?

 

[biswrest]

lincolnshibuya, I also got on the thread about the vacuum leak with the elbow that has the hole, and I checked mine out and it looked good! I have not disconnected the battery since I replaced it last summer.

 

[2Trux]

A dirty MAF can cause lean run codes, try cleaning it.

 

[biswrest]

Thanks 2Trux, I was thinking I might try that. Any thread out there on cleaning the MAF or where it is?

 

[swshawaii]

http://www.explorerforum.com/forums/showthread.php?t=339793&highlight=maf+cleaning

 

[biswrest]

Thanks guys, I cleaned the MAF sensor and IAC valve today and it's still running rough at idle. Is my next move changing the O2 sensor, upstream and bank 1?

 

[Number4]

Have you removed the throttle body and cleaned it? Also, you'll need to do the memory drain.

 

[biswrest]

Number 4 I have yet to clean the throttle body. After reading more on the threads my plan is to disconnect the battery. If that does not work then ill clean the throttle body and egr valve. Where is the the throttle body? I know it's close to the iac valve.

 

[Number4]

The throttle body is the first part of the engine that the air intake hose attaches to. In order to properly perform this task, you need to fully remove the TB from the engine. Four bolts and a gasket. It'll take 30 mins. From removal to install.
Purchase throttle body cleaner and a plastic brush (not steel or brass,) I think I used an old tooth brush.
Of course disconnect the neg. battery cable before unplugging the TB electrical connector. I'll post some links in a moment.

Cleaning the TB
https://m.youtube.com/watch?v=JPNnHU6PYbo


After cleaning the TB, follow the steps in this video. Follow all of them.
http://www.explorerforum.com/forums/showthread.php?t=396533

 

[biswrest]

all right, I cleaned the throttle body and since I had things apart, I changed the problematic elbow. the elbow was not in good shape and may have been the problem after all. I did the reset as instructed and it seems to be running well! Thanks everyone!